1. Technical Field
The present disclosure relates to an integrated circuit (IC) and method for driving a display and, more particularly, to a display driving IC capable of reducing the number of transmission lines for transmitting gray-scale data from a memory and a display driving method thereof.
2. Discussion of the Related Art
Liquid crystal display (LCD) devices are widely used for information processing devices such as notebook computers, PDAs and monitors. An LCD comprises a liquid crystal panel having a thin film transistor (TFT) substrate on which a TFT is formed, a color filter substrate on which a color filter layer is formed, and a liquid crystal layer interdisposed between the two substrates. An LCD device displays an image by applying a controlled electric field to the liquid crystal layer to control the alignment of the liquid crystal and the quantity of light transmitted.
An LCD panel includes pixels formed at the intersections of a plurality of scan lines for transferring a gate select signal and a plurality of data lines for transferring color data or gray-scale data.
Driving ICs for driving a display device such as an LCD commonly include a scan driver for driving the scan lines and a source driver for driving the data lines. The scan driver and the source driver can be integrated into a single chip. An example of a source driver circuit for an LCD is disclosed in U.S. Pat. No. 6,747,626. In the '626 patent, a source driver circuit for driving an LCD includes a shift register, a plurality of data inputs connected to the source driver circuit for receiving input data indicative of an image to be displayed on the LCD, a plurality of sample registers coupled to the shift register, and hold registers coupled to the sample registers.
FIG. 1A is a block diagram of a conventional display driving IC 20. Referring to FIG. 1A, the driving IC 20 for driving a panel 10 includes a source driver 21a and a memory 22a. The driving IC 20 receives a control signal CON from an external controller 30 and drives the panel 10. The memory 22a stores gray-scale data corresponding to frames of images to be displayed on the panel 10. The gray-scale data is transmitted to the source driver 21a through a scan port of the memory 22a. In this case, all of the bits of the gray-scale data representing a gray scale of one pixel are transmitted in parallel.
In general, the size of the memory 22b decreases as the LCD becomes smaller, but, as shown in FIG. 1B, reduction in the size of the source driver 21b is limited, for example, due to the voltage applied to the source driver 21b. The required wiring space increases the height of the chip in which the driving IC is formed, and an increase in height is often not an acceptable option.